Challenges and issues on measuring, modelling and managing the water resources under changing climate and cand use

This chapter highlights some challenges and issues facing those involved in the area of water resources management. In order to have a proper plan for water management, we need to accurately quantify the size of the available water resources. In this regard, we face issues related to the scale of the measurements and their representation. The chapter briefly describes the new technologies in some areas and presents two examples of suitable management models at field and catchment scales. It also highlights issues related to the sustainable water use and offers practical solutions to manage water more efficiently at field scale, where agriculture is the greatest water consumer. In addition, a reference is made to a possible increase in water supply through the use of non-conventional water resources and different rainfall harvesting techniques at different scales, up to catchment scale. Using the resources more efficiently has been highlighted as an important issue as well as the need for water policies to accommodate the new changes related to climate and land use taking into account the concepts of green economy, water footprint and water-food-energy-environment security in an integrated water resources management approach.